1. Field of the Invention
The invention relates to a computer key construction, more particularly to a computer key which moves smoothly and which generates less noise when operated.
2. Description of the Related Art
Referring to FIG. 1, a conventional computer key is shown to comprise a push button (A), a support member (B), an upright socket member (C) and a resilient biasing member (D). The push button (A) has a slightly concave top portion (A1) with a downwardly extending peripheral flange (A2). A mounting projection (A3) extends downward from the rear side of the top portion (A1). The support member (B) includes an upright tubular portion (B1) and a rectangular flange portion (B3) which projects radially outward from an intermediate part of the tubular portion (B1). The socket member (C) confines a receiving space (C2) therein and has a top wall which is provided with a through hole (C1). Referring to FIG. 2, the support member (B) is provided inside the receiving space (C2) of the socket member (C) such that the tubular portion (B1) of the former extends through the through hole (C1) of the latter. The mounting projection (A3) of the push button (A) is mounted fittingly on the tubular portion (B1) of the support member (B), thereby securing the push button (A) on the support member (B). The flange portion (B3) is in sliding contact with the inner wall surface of the socket member (C). Four legs (B2) extend downwardly from four corners of the flange portion (B3) so as to restrict downward movement of the support member (B) in the socket member (C).
The resilient biasing member (D) has a convex support portion (D1) which is disposed inside the receiving space (C2) of the socket member (C). The bottom end of the tubular portion (B1) rests on a top end of the support portion (D1). A conductive member (not shown) is secured on a rear side of the top end of the support portion (D1). The biasing member (D) urges the support member (B) upward so that the flange portion (B3) abuts normally against the top wall of the socket member (C). The resilient biasing member (D) is provided on top of a circuit board (not shown). The conductive member on the biasing member (D) is spaced normally from a conductive strip on the circuit board.
When the push button (A) is pressed, the support member (B) moves downward to compress the biasing member (D), thus achieving contact between the conductive member on the biasing member (D) and the conductive strip on the circuit board to signal a pressed key condition. When the applied force is released, the biasing member (D) expands to once more urge the support member (B) to the normal unpressed key condition, thereby breaking the electrical connection between the conductive member on the biasing member (D) and the conductive strip on the circuit board.
From the foregoing, it has been shown that the biasing member (D) provides the necessary force to return the support member (B) from the pressed key position to the initial unpressed key position. However, note that as the biasing member (D) urges the support member (B) upward, the flange portion (B3) of the latter impacts the top wall of the socket member (C), thereby generating a relatively loud noise which can affect the quality of the working environment.
Referring to FIG. 3, the four sides of the flange portion (B3) are in sliding contact with the inner wall surface of the socket member (C), thus permitting stable movement of the support member (B) relative to the socket member (C). However, because of the relatively large contact area between the flange portion (B3) and the socket member (C), a relatively large friction force is thus present. Therefore, smooth movement of the support member (B) is unattainable.